Ultrastructural demonstration of glucose-6-phosphatase activity and glycogen in skeletal muscles of newborn piglets with the splayleg syndrome

Abstract

Summary -The ultrastructural localization of glucose-6-phosphatase activity and glycogen were investigated in the longissimus dorsi and biceps femoris muscles of normal and splaylegged newborn piglets. Significant differences were ascertained in the distribution of the reaction product of glucose-6-phosphatase activity between the two groups of animals. A fine precipitate was found in the sarcoplasmic reticulum and in the perinuclear cisternae of normal piglet muscles. In splaylegged muscles, variable deposits of coarse reaction product were observed within the extremely dilated cistemae of sarcoplasmic reticulum at their periphery. Moreover, both longitudinal and transversal ultrathin sections of these muscles showed a reduced number of myofibrils and an increased accumulation of glycogen (especially within the large extramyofibrillar spaces) in comparison with muscles of normal piglets. splayleg / muscle ultrastructure / glucose-6-phosphatase / glycogen / pig Résumé ― Démonstration ultrastructurale de l'activité glucose-6-phosphatase et du glycogène dans les muscles squelettiques de porcelets nouveau-nés atteints du syndrome d'abduction des membres. La localisation ultrastructurale de l'activité glucose-6-phosphatase et du glycogène a été analysée dans des muscles (longissimus dorsi et biceps femoris) de porcelets nouveau-nés normaux ou atteints du syndrome. Des différences significatives ont été mises en évidence dans la distribution du produit de réaction de la glucose-6-phosphatase entre les deux groupes d animaux. Un fin précipité a été observé dans le réticulum sarcoplasmique et l'espace périnucléaire dans les muscles de porcelet témoin. Dans les muscles anormaux, des dépôts variables et grossiers du produit de réaction ont été localisés dans les vésicules très dilatées du réticulum sarcoplasmique. De

Genome-wide association study identifies candidate genes for piglet splay leg syndrome in different populations

“…In addition, RAB32 was also highlighted as an important potential gene regulating lipid metabolism [55]. Ultrastructural analysis of the muscle of PSL and normal piglets (longissimus dorsi and biceps femoris) clearly demonstrated that mitochondria were often located near the sarcolemma of the normal piglets, but presented within the sarcoplasm of the PSL, which resulted in the increased accumulation of glycogen in the muscles of PSL [11]. It should be noted that glycogen is the first energy store in the piglet at birth.…”

“…Histomorphological investigations described PSL as myofibrillar hypoplasia, however, which was not exclusive to PSL as this condition was also found in clinically normal piglets [10]. In addition, ultrastructural analysis of PSL muscles clearly demonstrated an increased accumulation of glycogen compared with the muscles of normal piglets [11]. Besides the histological studies, the expression of the atrophy marker FBXO32 highly increased in PSL muscles (semitendinosus, longissimus dorsi, and gastrocnemius muscles) [4].…”

Polymorphisms of HOMER1 gene are associated with piglet splay leg syndrome and one significant SNP can affect its intronic promoter activity in vitro

“…The cause of the PSL might relate to the abnormal glycogen metabolism [ 14 ]. Compared to the normal pigs, muscle fiber reduction and glycogen accumulation were observed in the longitudinal and transvers section of PSL pigs’ muscle tissues [ 20 ]. The distribution of glucose-6-phosphatase’s metabolites in longissimus dorsi and biceps femoris muscle were significant differences between PSL and normal pigs [ 20 ].…”

“…Compared to the normal pigs, muscle fiber reduction and glycogen accumulation were observed in the longitudinal and transvers section of PSL pigs’ muscle tissues [ 20 ]. The distribution of glucose-6-phosphatase’s metabolites in longissimus dorsi and biceps femoris muscle were significant differences between PSL and normal pigs [ 20 ]. Although there is no direct evidence that ARNT involved in regulating the glucose metabolism, it can form a heterodimer mixture with HIF-1α and HIF-2α which could affect the skeletal muscle type and glycogen metabolism [ 21 ].…”

Incidence of splayleg pigs in Nebraska litter size selection lines1

“…Additionally, they found that increased blood glucose and lower hemoglobin levels in SL pigs weighing less than 1 kg allowed for a greater transmission of macromolecules from sow colostrum. Antalikova et al (1996) added to this effort and reported that ultrathin sections of muscles from SL pigs had fewer myofibrils and greater accumulation of glycogen within the extramyofibrillar spaces than muscles of normal pigs.…”